A recent mobile phone stores a phone book in which telephone numbers are associated with names. There is also provided a push-to-talk (PTT) service which allows a person to communicate with a plurality of communication partners at the same time. Japanese Patent National Publication No. 2007-513592 discloses a technique in which a plurality of telephone numbers registered in a phone book are grouped in advance, and when a group is selected, calls are originated to the telephone numbers registered in the group.
On the other hand, a mobile phone has the function of storing telephone numbers of past communication partners as a communication history. It will be convenient if a telephone number selected from among the telephone numbers stored as the communication history can be registered into a group in the same manner as in the case of registering a telephone number selected from among the telephone numbers stored in a phone book into a group. The history information, however, includes only the telephone number of the communication partner that was used for the previous communication. In the event that more than one telephone number is assigned by a phone book to the user who is assigned that telephone number, the telephone numbers other than that telephone number included in the history information will not be able to be registered into a group.
[Patent Document 1] Japanese Patent Laid-Open No. 2007-513592